An optical network is known that transmits wavelength division multiplexing (WDM) light including multiple groups, for example, M groups of wavelengths each acquired by multiplexing (combining) optical signals of a predetermined bit rate on the order of GHz to THz for each of multiple wavelengths respectively corresponding to multiple wavelength channels (wave lengths or light paths) divided by, for example, 100 GHz in a predetermined communication wavelength band, from a predetermined optical node to a plurality of other optical nodes through multiple optical input fibers (e.g., m fibers) and multiple optical output fibers (e.g., n fibers) (the number of fibers may be or may not be constant between optical nodes) in parallel among the optical nodes. The number of the optical input fibers, for example, m, includes the number of optical fibers from a plurality of optical nodes, and the number of the optical output fibers, for example, n, includes the number of optical fibers to a plurality of optical nodes. In such an optical network, an optical cross-connect apparatus making up each optical node performs routing of wavelength division multiplexing optical signals transmitted through optical fibers directly in the form of optical signals on the basis of a wavelength, thereby implementing large-capacity transmission with low power consumption. For example, this corresponds to an optical cross-connect apparatus described in Patent Document 1.
Because a traffic amount is predicted to increase at an accelerated rate in the optical network due to the recent spread of ADSL and FTTH and the spread of services such as high-definition moving image distribution, it is desired to increase the numbers of wavelength paths and optical fibers, i.e., to further increase the scale of the optical cross-connect apparatuses making up the optical nodes.